# capacitance problem

Discussion in 'Physics' started by logearav, Oct 8, 2011.

1. ### logearav Thread Starter Member

Aug 19, 2011
248
0
A dielectric of dielectric constant 3 fills three fourth of the space between plates of a parallel plate capacitor. What percentage of the energy is stored n the dielectric?
My attempt to solve this is given in attachment.

File size:
5.3 KB
Views:
30
2. ### t_n_k AAC Fanatic!

Mar 6, 2009
5,448
783
C1 is the free space capacitance
C2 is the filled space capacitance

C1 & C2 are effectively in series

$C_1=\frac{\epsilon_0 A}{d/4}=\frac{4\epsilon_0 A}{d}$

$C_2=\frac{3\epsilon_0 A}{3d/4}=\frac{4\epsilon_0 A}{d}$

Where A is the plate area and d is the total plate separation distance.

So C1=C2

Being equal and in series they will each have half of the total voltage applied to the capacitance.

Having equal voltage & equal capacitance means they have equal energy - so they share half the total energy stored on their combined equivalent series capacitance.

Last edited: Oct 8, 2011
3. ### logearav Thread Starter Member

Aug 19, 2011
248
0
Thanks for the reply t_n_k. C1 and C2 are connected in series--is it implied?